beaTunes is an iTunes companion app capable of
automatically analyzing your music collection to
help you build better playlists. It analyzes BPM
(beats per minute), silence at the beginning or
end of a song, and the color (based on frequency
spectrum) of a given song. Some of the data is
stored through iTunes, and some is stored by
beaTunes itself. beaTunes can suggest albums that
would complement your music collection, display
music charts, and help you find and fix errors in
your song meta data, like typos and wrong genres.
It also allows you to blog about selected songs or
playlists.

relax is a program designed for the study of the dynamics of proteins and other macromolecules though the analysis of experimental NMR data. It supports exponential curve fitting for the calculation of the R1 and R2 relaxation rates, calculation of the NOE, reduced spectral density mapping, the Lipari and Szabo model-free analysis, study of domain motions via the N-state model (or ensemble analysis) and frame order dynamics theories using anisotropic NMR parameters such as RDCs and PCSs, the investigation of stereochemistry in dynamic ensembles, and the analysis of relaxation dispersion.

DansTuner is a program to tell you if you are playing a
pitch in tune. Major features include automatic discovery
of which note you are trying to play (good for trumpet,
singer, etc.), the ability to play a guide tone at a
configurable volume, a graphical moving "needle" with a
red/green display and detail about how flat or sharp you
are, and an easily configurable background noise
threshold.

glScope is an audio oscilloscope program that uses
OpenGL, GLUT, and ALSA. The UI is sort of an
experiment in more fluid, intuitive interfaces,
and therefore is a departure from the traditional
fixed-grid-knobs-and-switches interface on most
real oscilloscopes.

Twibright Pitchotron analyzes any MP3 into the
semitones that are being played, displayed in a
scrolling coloured graph on a video. It aids
musical transcription. It includes coloured piano
key stickers that enable accompanying arbitrary
music and improvising even to musical analphabets.